CALCULOGENIC POTENTIAL OF GALACTOSE AND FRUCTOSE IN RELATION TO URINARY-EXCRETION OF LITHOGENIC SUBSTANCES IN VITAMIN-B-6 DEFICIENT AND CONTROL RATS

Objective: Calculogenic potential of refined sugars galactose and fruc tose was examined in vitamin B-6 deficient and control rats in terms o f their capacity to increase urinary excretion of lithogens. Methods: Male albino rats were fed vitamin B-6 deficient diet with 51.7% sucros e + starch or galactose or fructose as the source of carbohydrate. Pai r-fed controls were maintained for all the groups for a period of four weeks. Twenty-four hour urine samples obtained at weekly intervals we re analyzed for creatinine, calcium, oxalate, phosphate and uric acid. Microscopic urinalysis was performed at the end of the study. Results : Urinary calcium excretion increased with respect to baseline in all groups except vitamin B-6 control group. On day 28, galactose and fruc tose-fed rats demonstrated significant hypercalciuria as compared to t he sucrose + starch fed group. Vitamin B-6 deficient rats (irrespectiv e of the sugar fed) excreted significantly greater urinary calcium com pared to pair-fed controls. Oxalate excretion was significantly increa sed in rats fed galactose compared to those fed fructose or sucrose starch. Vitamin B-6 deficiency further increased oxalate excretion by 1.5, 1.9 and 1.7 fold in sucrose + starch, fructose or galactose fed a nimals, respectively. Urinary uric acid excretion was enhanced only in fructose-fed rats. There was no change in urinary excretion of creati nine and phosphate in different experimental and control groups. Incre ased urinary saturation with lithogens caused pronounced crystalluria in all the vitamin B-6 deficient groups as well as galactose control g roup. Conclusion: The results suggest galactose ingestion is associate d with a greater propensity to form calcium oxalate kidney stones than fructose. Calculogenic potential of galactose and fructose is further enhanced in vitamin B-6 deficiency.